The ActiveFlag property controls which dimensions get loaded. You can set this property on the Dimension Settings tab of the Decision Cube editor using the Activity Type control. When this control is set to Active, the dimension is loaded unconditionally, and will always take up space. Note that the number of dimensions in this state must always be less than MaxDimensions, and the number of summaries set to Active must be less than MaxSummaries. You should set a dimension or summary to Active only when it is critical that it be available at all times. An Active setting decreases the ability of the cube to manage the available memory. 

When ActiveFlag is set to AsNeeded, a dimension or summary is loaded only if it can be loaded without exceeding the MaxDimensions, MaxSummaries, or MaxCells limit. The decision cube will swap dimensions and summaries that are marked AsNeeded in and out of memory to keep within the limits imposed by MaxCells, MaxDimensions, and MaxSummaries. Thus, a dimension or summary may not be loaded in memory if it is not currently being used. Setting dimensions that are not used frequently to AsNeeded results in better loading and pivoting performance, although there will be a time delay to access dimensions which are not currently loaded.